FIELD OF THE INVENTION
The invention relates to a method for switching voltages higher than a supply voltage, on a semiconductor chip through the use of a circuit configuration, including a first series circuit having a first p-channel transistor and a first n-channel transistor and being connected between a terminal for a first high potential and a terminal for a first low potential; a second series circuit having a second p-channel transistor and a second n-channel transistor and being connected between the terminal for the first high potential and a first input terminal; a junction point of the two transistors of the first series circuit being connected to a gate terminal of the second p-channel transistor and forming a terminal for an output signal; a junction point of the transistors of the second series circuit being connected to a gate terminal of the first p-channel transistor; a gate terminal of the second n-channel transistor forming a second input terminal; a third series circuit having a third p-channel transistor and a third n-channel transistor and being connected between a third input terminal and the terminal for the first low potential; the junction point of the two transistors of the first series circuit being connected to a gate terminal of the third n-channel transistor; a junction point of the transistors of the third series circuit being connected to the gate terminal of the first n-channel transistor; and a gate terminal of the third p-channel transistor forming a fourth input terminal.
Such a circuit configuration is disclosed in a paper in Proceedings ISSCC 1991, page 260. In that case, the gate terminal of the first n-channel transistor is connected to the gate terminal of the first p-channel transistor. In addition, the first low potential is equal to the earth or ground potential.
In the case of circuits integrated on semiconductor chips, it is often necessary to supply further voltages in addition to the customary operating voltages of, for example, +5V and 0V for TTL and CMOS, which further voltages may be significantly higher or even negative, or to generate the further voltages on the chip from the operating voltages and, if appropriate, to switch them on and off. If such semiconductor chips contain non-volatile memories such as, for example, EPROMs, EEPROMs or flash memories, programming voltages are required for them which must have values in the range of 12V to 20V or may even be negative, depending on the memory concept. The known circuit configuration serves to switch a relatively high programming voltage. However, negative voltages cannot be switched by that known circuit configuration.